Gardening by Month - December

Houseplants

• During the winter, houseplants typically need less water than in the summer due to reduced hours of sunlight. Err on the side of caution and use tepid water instead of cold water. Overly wet soils can lead to increased numbers of fungus gnats that lay eggs in the wet soil. 

• When purchasing houseplants during the winter, be sure to protect the foliage from the cold on the trip home. Place plants in a cardboard box or other protective covering to prevent damage to leaves.

• On extremely cold nights, move houseplants back from icy windows to prevent chilling injury.

• Holiday poinsettias do best with bright, indirect light and night temperatures in the 50-60's. Keep plants away from drafts, registers, and radiators. Let the soil dry only slightly between thorough waterings. Ensure the water can drain and evaporate; punch holes in the decorative foil if needed.

• Be sure to check houseplants often for common pests: aphids, spider mites, scale, mealybugs, whiteflies, and thrips.

Trees & Shrubs

• Only female hollies bear the red berries. There must be a male tree nearby for pollination and fruit production to occur.

• Branches of apples, pears, and other rose family plants that were infected with fireblight can be safely pruned off now. Another option is to wait until a dry period during mid-summer.

• Be sure the root zones of shrubs are thoroughly mulched. Any organic material will do.

• Live Christmas trees hold needles longer when you make a clean, fresh cut at the base and always keep the trunk standing in water.

• Hollies may be trimmed now. The cuttings can be used in holiday decorations. 

Miscellaneous

• Monitor overwintering dormant plants, bulbs, and tubers by ensuring they are not completely dried out or rotting. 

• Check to see if any seeds purchased for the next season require stratification in order to germinate. The seed packet should indicate if this process is needed. Some common seeds that require stratification include Asclepias, Echinacea, Rudbeckia, and Baptisia. Mimic cold stratification as needed by placing seeds in the refrigerator at 33-40⁰F for 1-3 months.